Supposition(n.) The act of supposing, laying down, imagining, or considering as true or existing, what is known not to be true, or what is not proved.
Supposition(n.) That which is supposed; hypothesis; conjecture; surmise; opinion or belief without sufficient evidence.
Suppositional(a.) Resting on supposition; hypothetical; conjectural; supposed.
Suppositive(a.) Including or implying supposition, or hypothesis; supposed.
Suppositive(n.) A word denoting or implying supposition, as the words if, granting, provided, etc.

Words within supposital